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leetcode Verify Preorder Serialization of a Binary Tree

One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we record using a sentinel value such as #.

1
2
3
4
5
6
7
8
     _9_
    /   \
   3     2
  / \   / \
 4   1  #  6
/ \ / \   / \
# # # #   # #

For example, the above binary tree can be serialized to the string "9,3,4,#,#,1,#,#,2,#,6,#,#", where # represents a null node.

Given a string of comma separated values, verify whether it is a correct preorder traversal serialization of a binary tree. Find an algorithm without reconstructing the tree.

Each comma separated value in the string must be either an integer or a character '#' representing null pointer.

You may assume that the input format is always valid, for example it could never contain two consecutive commas such as "1,,3".

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leetcode Patching Array

Given a sorted positive integer array nums and an integer n, add/patch elements to the array such that any number in range [1, n] inclusive can be formed by the sum of some elements in the array. Return the minimum number of patches required.

Example 1: nums = [1, 3], n = 6 Return 1.

Combinations of nums are [1], [3], [1,3], which form possible sums of: 1, 3, 4. Now if we add/patch 2 to nums, the combinations are: [1], [2], [3], [1,3], [2,3], [1,2,3]. Possible sums are 1, 2, 3, 4, 5, 6, which now covers the range [1, 6]. So we only need 1 patch.

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博主大清早在被窝里看看手机，浏览下博客，发现 Error establishing a database connection，显然是数据库挂了= =

貌似就是作死直接LAMP的下场（linux + apache +mysql + php）

博主立刻从床上弹起来，开电脑，重起mysql，就又可以了。

那么，虽然博主最近起不来→_→今天因为这个立马爬起来，但是总不能老是出错吧！

于是开启了优化方案。。发现是由于apache内存占用太高导致mysql没内存用了

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站点自从开启 https 之后 ，百度分享就不能用了！但是又寻找不到类似百度分享的替代品。。

怎么办呢？要如何解决 百度分享不支持https的问题呢，

跟着博主动动手，让你百度分享仍然能在https下使用 ~

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leetcode Longest Increasing Path in a Matrix

Given an integer matrix, find the length of the longest increasing path.

From each cell, you can either move to four directions: left, right, up or down. You may NOT move diagonally or move outside of the boundary (i.e. wrap-around is not allowed).

Example 1:

nums = [

[9,9,4],

[6,6,8],

[2,1,1]

]

Return 4 The longest increasing path is [1, 2, 6, 9].

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leetcode Odd Even Linked List

Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.

You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.

Example: Given 1->2->3->4->5->NULL, return 1->3->5->2->4->NULL.

Note: The relative order inside both the even and odd groups should remain as it was in the input. The first node is considered odd, the second node even and so on ...

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Lowest Common Ancestor of a Binary Tree 问题描述

Given a binary tree, find the lowest common ancestor of two given nodes in the tree.

给定一棵二叉树，求最近公共祖先。

最近公共祖先定义为：“对于有根树 T 的两个结点 p、q，最近公共祖先表示为一个结点 x，满足 x 是 p、q 的祖先且 x 的深度尽可能大（一个节点也可以是它自己的祖先）。”

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